svn commit: r249461 - head/sys/dev/ips

[John Baldwin]

On Wednesday, April 17, 2013 1:15:11 pm hiren panchasara wrote:
> On Tue, Apr 16, 2013 at 9:10 AM, John Baldwin <jhb at freebsd.org> wrote:
> > On Saturday, April 13, 2013 10:42:40 pm Hiren Panchasara wrote:
> >> Author: hiren
> >> Date: Sun Apr 14 02:42:40 2013
> >> New Revision: 249461
> >> URL: http://svnweb.freebsd.org/changeset/base/249461
> >>
> >> Log:
> >>   Fixing a clang warning indicating uninitialized variable usage.
> >>
> >>   PR: kern/177164
> >>   Approved by:        sbruno (mentor)
> >
> > Hmm, I always thought that dmatags and maps were opaque types and not
> > necessarily "known" in consumers to be pointers.  (Some drivers do check tehm
> > against NULL implicitly via 'if (map)' or 'if (tag)', but well-behaved drivers
> > use other means (flags, etc.) to know if they are valid.)
> 
> Hi John,
> 
> Would this be a better fix? We do not need to do any clean up if we
> fail to create the tag:
> 
> Index: ips.c
> ===================================================================
> --- ips.c       (revision 249588)
> +++ ips.c       (working copy)
> @@ -578,7 +578,7 @@
>  {
>         int error;
>         bus_dma_tag_t dmatag;
> -       bus_dmamap_t dmamap = NULL;
> +       bus_dmamap_t dmamap;
>                 if (bus_dma_tag_create( /* parent    */ sc->adapter_dmatag,
>                                 /* alignemnt */ 1,
>                                 /* boundary  */ 0,
> @@ -595,7 +595,7 @@
>                                 &dmatag) != 0) {
>                  device_printf(sc->dev, "can't alloc dma tag for
> statue queue\n");
>                 error = ENOMEM;
> -               goto exit;
> +               return error;
>          }
>         if(bus_dmamem_alloc(dmatag, (void *)&(sc->copper_queue),
>                             BUS_DMA_NOWAIT, &dmamap)){

That would be fine.  I would actually prefer though that this only
call bus_dmamem_free() if the alloc succeeds, so in addition I would
make the call to bus_dmammem_free() conditional on sc->copper_queue != NULL.

Thanks.

-- 
John Baldwin